DE1558628B2 - Process for the production of an oxidation-resistant copper alloy - Google Patents

Description

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The invention relates to a method for the manufacture [- that they less over a wide temperature range

development of oxidation-resistant copper alloys with oxidation-resistant.

It is also known that a copper alloy that

permanence in moist or aggressive atmos from 1 to 5 ° / o aluminum, 1 to 4 ° / ₀ silicon and

sphere. 5 consists of iron, up to 0.3% phosphorus, the remainder copper,

Copper alloys are used in industry and business to increase strength and relieve stress

Shank of parts made from such an alloy was widespread in a wide variety of fields

Application found. However, the numerous cold upsetting are to be made, such as screws,

to subject advantageous physical properties of this alloy to a quenching and annealing at 450 ⁰ C,

rations practically without exception due to their extremely io Although the seawater resistance of this well-known

low resistance to oxidation and tarnishing, highlighted in the alloy, can be derived from the

especially in a humid and aggressive atmosphere, but the measures were not based on a planned one

impaired. Improvement of the resistance to oxidation under

The development of copper alloy formation has long been a corrosion-inhibiting protective layer

ments without this disadvantageous property, d. H. from 15 to be closed, even when cooled down

Provides extensive tarnish protection through good oxidation and / or tarnish resistance. Here-

copper alloys characterized by the fact that in the

Efforts of the copper industry. She sought the relevant specialist literature additions of silicon,

winding new copper alloys with a min- tin, iron and cobalt to common aluminum

At least the stainless, austenitic steels and bronzes have no particular effect in this regard

inherent resistance to oxidation and tarnishing. is attributed.

The path taken so far to solve the problem was the investigation of the oxidation and German patent application P 15 33 342.3-24 running properties of binary copper alloys whose (O 11483 / 40b) is a method for producing binary Alloy additive, e.g. B. aluminum, a strong copper alloy with a very high oxidation-reducing effect and is able to build up the oxide film with good protection resistance over a wide temperature range. However, it was suggested on this one. According to this proposal, copper will not be able to produce alloys with the intrinsic 2 to 25 percent by weight of a two-element shaft that is alloyed with those of corrosion-resistant alloy additives whose first resistant steels corresponded to the damaged 30 element aluminum, gallium, Indium or beryl protective films close again by themselves. lium, the second element of which is silicon, germanium, a partial success was achieved by being tin or beryllium, with the proviso that in binary alloys subjected to a treatment, in this case aluminum is the first element, if the alloy additive, but not the copper beryllium is the second element. The weight matrix was oxidized (compare, for example, BLE Price 35 ratio of the first to the second element and GT Thomas, "Journal of the Institute of 0.03: 1 to 10: 1. This alloy is under oxy-metals", 63, p . 21 [1938]). As a rule, one of these processes with selective oxidation was used for at least 1 minute under these conditions, temperature from 400 ° C to the fixed point temperature by heating the binary alloys in atmospheres. This forms a highly heated 25 to 5000 angstroms, which, like z. B. moist hydrogen, 4 ° thick outer layer of copper oxide and oxides, although the reducing alloy component, not the alloy additives mentioned and a second but could oxidize the more noble copper. This oxidation-resistant treatment immediately below this often produces invisible protective films of at least 50 angstroms thick, consisting of oxides of the alloying additive. These films are discrete dispersion of at least one of the alloy protect the copper matrix, as long as it does not contain complex oxide containing additives, mechanical stress can be destroyed. Under particularly favorable conditions is a her, which even in bright and shiny surface Umformungsver- generated which oxyfahren under mild conditions with less than 1 ° / ₀ dationsbeständig but destroyed. Often, however, the external plastic deformation, such as when aligning layer has a dappled or darkened appearance, is the case of sheet metal, so form at normal temperature refined, oxidation-resistant layer atmosphere by itself does not expose any new, closed, which give the alloy a considerable protective film free of copper oxide. Gives protection.

In U.S. Patent 3,259,491 an oxy- The present invention is linked to the predation-resistant Copper alloy, the proposal discussed above and represents a by alloying copper with at least an improved copper alloy available in the two alloy components in such quantities - the oxidation and tarnishing resistance of both the conditions can be established that certain grains of the first as well as the second layer are considerably complexed Oxide is formed on the surface of the alloy. This is especially surprising since it has already been be det. The alloy constituents are thus added to the proposed copper discussed above in proportions that give the alloy a considerable oxidation and tarnishing surface of the alloy in relation to the concentration resistance.

tration of the individual alloy components in the grain. It was found that the first, i.e. H. the outer

diffuse plexen oxide. The alloy layer described (1) actually consists of two layers (la) and

stanchions have a high resistance to oxidation. It consists of 65 (Ib), the outermost layer (la) of which is very rich

are particularly advantageous at elevated temperatures on copper oxides, while the inner layer (Ib)

and show strong resistance to oxidation e.g. B. when rich in oxides is one of the alloying elements.

800 ° C. However, the alloys have the disadvantage that, according to the invention, further alloying

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elements phosphorus, arsenic, antimony and / or wis- from aluminum to silicon between 2.5: 1 to mut, which the oxidation and tarnishing is 0.5: 1. For the elements with lower greatly increase the resistance of the inner layer (1b). or higher atomic weight than aluminum Furthermore increase the additional alloy elements- quantitative ratio can be adjusted accordingly, elements phosphorus, arsenic, antimony and / or bismuth, 5 When using beryllium and silicon, a which are used according to the invention, the Oxyda quantitative ratio of 2: 1 to 0.15: 1 is used, tion and tarnishing resistance of the second, very oxy- When using indium and silicon is dation-resistant layer (2). the quantitative ratio 10: 1 to 0.2: 1. When using

The invention thus relates to a process for the production of gallium and silicon in the amount Production of an oxidation-resistant copper ratio of 10: 1 to 0.2: 1, in the case of the aluminum system. alloy, which is characterized in that germanium 5: 1 to 0.2: 1, in the case of the Alumi system

nium-tin 3: 1 to 0.03: 1. For the AIu-

(A) Copper is alloyed with 0.01 to 0.50 weight of minium-beryllium, the proportion is percent phosphorus, arsenic, antimony, bismuth or io _: \ up to 0.5: 1, with gallium-germanium 5: 1 to mixtures of which and 2.0 to 25.0 weight ₁₅ o, 1: 1, for gallium-tin 3: 1 to 0.1: 1, with a percentage of two elements, the weight medium-germanium 10: 1 to 0, 2: 1 and with a ratio of the first to the second element between dium tin 5.0: 1 to 0.1: 1.

0.03: 1 and 10: 1, and the first element is the exact 'quantity ratio of the first element

Aluminum, gallium, indium or beryllium _{and zwe} i n _th element depends on the atomic weight of the second element is silicon, germanium, tin respective element _20, the special complex oxy or beryllium, with the proviso that the aluminum, the should be formed, as well as of the minium is the first element, if beryllium diffusion properties and the chemical properties is the second element, on which one shanks the respective elements.

(B) the alloy produced according to (A) under oxy- _u . ^D * ^e J ^ ^{c ycle} S ^{of the} invention also receives 0.01 exploding conditions of at least 1 minute ^{25 b 's} °' ⁵⁰ weight percent of phosphorus, arsenic, antimony long to a temperature of more than 400 to bismuth or a mixture thereof The preferred proportion of 850 ⁰ C. heated to is 0.05 to 0.20 percent by weight. The preferred element is phosphorus.

(1) a first outer layer (1) from 25 to According to the invention, the way in which the 5000 Angstrom strength is formed, the ₃₀ copper is alloyed with the alloy additives, of

(A) contains an outer partial layer (la) which is of minor importance. The conventional Mreich of copper oxides, and methods can be used with the

(b) has an inner sub-layer (Ib) which would give the molten copper to which the alloy rich are incorporated into oxides of the first element, is oxygen-free, is, and 35 so that the alloying elements before solidification of the

, -. . . ,. , .... ",. ,, ". Alloys do not exist in the form of their oxides.

(2) a second oxydationsbestandige layer (2) _Di * ^ _{Elen duck can be pure or as ow} loading _{ki Before} immediately below the first layer (1) _{as usual.}

sits that has a discrete (remote) dispersion % _n ^? _{Meikmal of the} association according to the invention at least one of the alloy _{constituents is 40 per} | _{oh; that the solidified and} g _ege appropriate, of the two elements and parts containing _{grain-to dnem matching or gewünschtei].} Workpiece ausplexen oxide containing and wherein the second _shaped l _{egiemng under} oxidizing conditions at least 50 Angstrom layer is strong, ^ _{hile mi} ^ _s ^ _{deste Einei} - _{5 vorzugswe} i _se least woraut to _{5 minutes at a} temperature of more than 400 to

(C) the first partial layer (la) is preferably removed. 45 85O ° C is heated. Temperatures from 180 to 400 ⁰ C

are not sufficient for the formation of the second layer (2),

According to a preferred embodiment, only the first layer (1) can be formed, which consists of another alloy additive, the outer sublayer (1) and the inner sublayer (1b), namely either cobalt, cerium or iron or a. At temperatures above 400 ^° C., a mixture thereof, namely in a total amount of 50, probably the first as well as the second layer is formed. 0.05 to 5.0 percent by weight, preferably 0.2 to According to a preferred embodiment

0.8 percent by weight. Cobalt is the preferred addition to the alloy in an oxidizing atmosphere, e.g. B. at sentence. Through these alloy additions, the oxygen air is at a speed of at least anti-aging properties of the alloy of 5 ° C / hour. heated to the desired temperature. Invention further improved. 55 Of course, the treatment temperature

As stated above, 2.0 to 25 Ge depending on the particular system and on the weight percent of the two elements alloyed with copper. each desired properties may be different. The preferred total amount is between 2 and In the preferred embodiment Tempe-7 Weight percent. The relative proportions of the temperatures from 500 to 800 ° C are used. The time, first to second element must be in the range of 60 which will keep the alloy at this temperature 0.03: 1 to 10: 1. That is for a certain, should in practice not exceed two days, The system of selected proportions can, if desired, be given within longer times Above specified range can be used in a wide range. The optimal heating limits vary, and it depends on the duration is 1 to 10 hours, ligen system and the relative atomic weight of the 65 It is absolutely necessary that the alloy under given elements. When the two elements are heated to oxidizing conditions, each minium and silicon are the most preferred oxidizing media, e.g. B. preferably air or Are alloying elements, the proportion should be oxygen, or an oxidizing salt melt,

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ζ. B. a salt melt containing sodium nitrate, the thickness of the first layer (1) depends on the

can be used. respective treatment conditions. Your strength

After the treatment under the above, however, at least 50 angstroms. To achieve

The alloy should be sufficiently resistant to oxidation

temperature cooled. 5 second layer (2) at least 50 angstroms and

The method according to the invention provides an alloy that is preferably at least 200 angstroms thick. the

with a first outermost layer (1) and a maximum thickness of the second layer (2) depends entirely on

second extremely oxidation-resistant layer (2). constantly from the treatment conditions and the

The first outermost layer (1) is 25 to 5000 angstroms whatever system used; i.e., longer hold times strong, and it contains an outer partial layer (la), the io and higher temperatures result in a stronger second

is rich in copper oxides, as well as an inner partial layer (2). Preferably, however, the second layer should

layer (Ib), rich in oxides of the first element (2) have a thickness of about 0.05 mm. For some

is, d. H. either aluminum, gallium, or indium purposes, however, it may be cheaper yet a thicker one

Beryllium. To form the second extremely oxidation-resistant second layer (2) or a second layer Layer (2) lies immediately below the first layer 15 (2) which is made up of all of the rest of the alloy

(1), it is at least 50 angstroms strong, and it arises.

holds a discrete dispersion of a complex oxide, the second, highly oxidation-resistant layer (2) that contains at least one of the two elements. is characterized in that it is a discrete As indicated above, there is a dispersion of complex oxides containing the at least the first layer (1) consists of two sub-layers, 20 at least one of the two elements mentioned. the of which the outer partial layer (la) is mainly made up of discrete dispersion is in the metal matrix. Copper oxides. This sub-layer is in the eye- In the copper alloy of the invention has the mine colored, and it adds little or no to the second layer (2) a shiny and light appearance Resistance to oxidation or tarnishing. Therefore it results in a very high oxidation and tarnishing preferably removed them. The strength of this resistance over a wide temperature range Partial layer (la) depends on the temperature used to form it at or below the deformation temperature Temperature. area. In other words, the oxidation and tarnishing resistance of the inner sub-layer (Ib) of the first layer are bright and shiny mainly made of oxides of aluminum, an alloy that has the desired properties - gallium, Indium or beryllium. This sub-layer has 30 th of alloys of this type, and this yields its own Considerable oxidation and start-up activities are in a wide temperature range persistence. This layer is transparent, it remains up to the temperature of the heat treatment stage before the original shine and color of the hands. This second layer (2) behaves chemically, Substrate alloy. The one in the patent application as if it were more noble than copper, i.e. i.e., it is permanent P 15 33 342.3-24 (O 11 483 / 40b) proposed le- 35 against the attack of chemicals that cause normal regeneration after one to two months discolored can be used for pickling copper. A sufficient number of places on the second layer, below the second layer (2) is normally the same that the counterparts made from this alloy have the copper base alloy. These copper stands become unsightly. In the case of the copper alloy, the basic alloy has only the original oxidation element Invention occur even after a long time, e.g. B. 40 resistance.

After one year of weathering in an industrial atmosphere, it is particularly surprising that by adding only very few fine discolored spots on the inside of one of the elements mentioned phosphorus, arsenic, Partial layer (Ib) on, and from this alloy antimony and bismuth the oxidation and start-up produced Objects are still bare resistance of the partial layer (Ib), especially the and shiny. This is due to the addition of the 45 tarnishing resistance, which is considerably improved. Next elements Phosphorus, arsenic, antimony and / or wis- is the resistance to oxidation and tarnishing of the mut, which also improves an antioxidant effect on the second layer (2), in particular Partial layer (Ib) exert, although not as discrete, the resistance to oxidation.

Dispersion present in this layer. Dementspre- By adding cobalt, cerium or iron is Accordingly, for practical purposes, the partial layer (1b) 50 results in a further improvement of the oxidation legs adequate resistance to oxidation and tarnishing. durability of the alloy achieved. The oxidation at The copper oxides of the first outer partial layer (la) at elevated temperature hardly produce any grain growth easily removed, e.g. B. by dissolving. Forms by adding cobalt, cerium or iron with dilute sulfuric acid. What remains is a fine dispersion of the additive and / or inner sub-layer (Ib), which is particularly resistant to the intermetallic compound oxidation formed with them and is starting. If these have inner parts, which inhibits grain growth. on layer (1 b) must be removed, e.g. By pickling, in this way the alloy of the invention contains one Buffing, etching or reshaping, or if fine dispersion rich in cobalt, cerium or this sub-layer (Ib) is mechanically damaged, is iron.

results in the improved second layer (2), which is resistant to oxidation and tarnishing, as well as further protection.
The element from the group of phosphorus, arsenic,

Antimony and bismuth improve the properties of the second layer (2) in Example 1, however

this effect is less pronounced than in the 65 Using pure copper and the purest Partial layer (Ib). As in the partial layer (Ib) alloy additives, a copper alloy was used this element is not posed as a discrete dispersion in the. The alloy was made second by means of a tilting mold Layer (2) present. tion into a 44.45 x 44.45 x 101.6 mm bar

potted, heated to 871 ° C, rolled down in several passes to a thickness of 4.8 mm and through Cold rolling and annealing formed into a 0.254 mm thick sheet. The content of alloy components Table I shows the copper alloys obtained. . ■■. '.!

aluminum
% Silicon
% Table I. cobalt
% cerium
% Arsenic '
% alloy 3.0 2.0 phosphorus
% A. 3.0 2.0 B. 3.0 2.0 0.10 0.3 C. 3.0 2.0 0.10 - 0.10 D. 3.0 2.0 0.10 - - 0.50 E. -

Example 12

The 0.254 mm thick sheets produced according to Example 1 from alloys A, B and C were carefully cleaned and ^{heated to various temperatures between 350 and 800 °} C. in air for 2 hours. The weight increase in y / cm ² is given in Table II.

Table II

alloy

A.
B.
C.

Weight increase in y / cm ²
350 ° CI 450 ° C 600 ° CI 800 ° C

8.5
5.1
3.6

7.5
5.0
3.2

12.2
6.3
5.6

31.5
32.5
22.0

It can be seen that the alloys B and C, that is the alloys with phosphorus or phosphorus and cobalt, the film growth at lower oxygen uptake at temperatures of 600 ⁰ C or below substantially ceased.

Example 3

The alloys obtained after the treatment according to Example 2 A, B and C were oxidized at temperatures of 450, 500, 550, 600, 650 and 700 ⁰ C and immersed for removing the outer part-layer (1 a) in dilute sulfuric acid. The inner sub-layer (Ib) is exposed here. All samples are shiny and bright. The samples were weathered for several months on the roof in an industrial atmosphere. The following results were obtained. Alloy A: The Pi above treated at all temperatures had a mottled and piebald appearance. Alloys B and C were shiny and bright with no stains. The heated at 500 to 450 ⁰ C alloys B and C showed a slight haze, but were still shiny.

Example 4

This example illustrates the antioxidant properties of the partial layer (Ib) of the alloys of the invention. The alloys A and B were heated according to Example 2 at 600 ⁰ C, pickled in dilute sulfuric acid to expose the outer Tielschicht (1 a) to be removed and the internal sublayer (Ib). The parallel resistance of a certain area of the layer was measured with an AC capacitance bridge. At a frequency of 1 kHz, alloy B had a peak resistance of 80,000 ohms for a 1 cm ^{2 area} compared to only 20,000 ohms for alloy A. This shows that alloy B with the phosphorus addition was four times higher has electrical resistance than alloy A and is four times better electrical insulator.

Example 5

This example illustrates the improved resistance to oxidation of the second layer (2). The alloys A and B were ^{heated to 800 °} C. for 2 hours according to Example 2. The first layer (1) of the two samples including layers (1 a) and (1 b) was removed by strong acid pickling. About 5000 y / cm ^{2 were} removed from each sample. Each sample was eihitzt then for 2 hours in an oxidizing atmosphere at 45O ⁰ C. With alloy B, no weight increase could be determined within the accuracy limit of the balance (approx. 0.5 y / cm ² ), while with alloy A a weight increase of 2 y / cm ^{2 was} measured.

Example 6

This example explains the special properties of layer (Ib) in alloy C. Alloy C was heated to 650 ° C. in an oxidizing atmosphere as in Example 2, treated as in Example 4, and the parallel resistance as in Example 4 was measured. At a frequency of 1 kHz, alloy C showed a peak resistance of 103,000 ohms, based on an area of 1 cm ² .

Example 7

In this example, the alloy C according to Example 2 was heated for 2 hours at 65O ⁰ C. The outer part-layer (1a) was removed by pickling with sulfuric acid, and the inner part-layer (Ib) was removed with a sand-steel blower. The sample was weathered in an industrial atmosphere for several months. It retained its original golden sheen and did not have a dappled or cloudy appearance.

Example 8

The 0.254 mm thick sheets of alloys D and E produced according to Example 1 were ^{heated to 800 °} C. for 2 hours according to Example 2, then immersed in dilute sulfuric acid in order to remove the outer partial layer (1a) and the inner partial layer (Ib) to expose. The obtained samples looked shiny and bright. The samples were weathered according to Example 7 for several months. They retained their original golden sheen and did not look dappled or cloudy.

009585/166

Claims (3)

Patio-legal principle: 1. Process for the production of an oxydätidris'-resistant Copper alloy, characterized by gel e η η that one (A) Copper alloyed with 0.01 to Q.5 weight percent, preferably 0.05 to 0.20 percent by weight, Phosphorus, arsenic, antimony and / or bismuth and with 2.0 to 25 percent by weight, preferably 2 to 7 percent by weight, one of two in a weight ratio of 0.03: 1 to 10: 1 mixed elements of existing L6 alloy additive, its first element aluminum, gallium, indium or beryllium ~ and its second element silicon, Germader Maß-Element isj :, the second element is if Uli,!.! S. on what around 20th (B) the alloy produced according to (A) under oxidizing conditions for at least 1 minute to a temperature greater than 400 to 850 ° C 'heated wildly until (I) an outer layer. (1) is formed in a thickness of 25 to 5000 angstroms, which (a) contains an outer part (la); which is rich in copper oxides, as well
(b) an inner sublayer (Ib) that is rich aii is oxides of the first element, as (II) a second oxidative oil resistant layer (2) that is immediately below it, is at least 50 Åägström thick and one discrete dispersion of a complex containing at least one of the two elements contains dxyds. 2. The method according to claim 1, characterized in that the first partial layer of the alloy (la) is removed. 3. The method according to claim 1; therefor, ch, marked, that the alloy is additionally. 0.05 to 5 percent by weight, preferably!)! ^ To 0.8 percent by weight, cobalt, cerium or. Iron wasteland, mixtures thereof; preferably cobalt; be alloyed.